This invention relates generally to fluid pressure devices. More particularly, it relates to hydraulic pumps or motors of the gerotor type wherein a ring gear orbits and a star gear rotates. The mechanism for effecting orbital movement of the ring gear also controls the porting of fluid into and out of the fluid chambers defined between the gears.
In recent years there have been many improvements in gerotor type pumps and motors. Some such devices incorporate a fixed ring gear within which a star gear is supported for orbital and rotational movement. A wobble shaft necessarily is associated with the star gear in order to compensate for its orbital movement. Other such devices include an orbital ring gear and a rotatable star gear, so as to eliminate the necessity of the wobble shaft. Devices of this nature heretofore have required complicated valving arrangements for controlling the porting of fluid into and out of the fluid chambers between the gears.
There remains a need for a fluid pressure device of the gerotor type having an externally toothed star gear rotating within an internally toothed ring gear, wherein the ring gear is supported for orbital movement and includes a mechanism for efficiently controlling the flow of fluid to and from the device. There is a further need for such a device which is susceptible of precise and economical manufacture and efficient operation.